I cant tell you exactly what is plugged into HDC it is the master on the seconday IDE channel however. The error probably has nothing to do with the load, the load appears to be related to apache and not to cPanel however. I suggest looking over your users usage.

You will need to have your system admin/datacenter look into it. It could be anything from a cd-rom drive with a bad disk into it to a hd that is failing to a HD controller that is reporting back improperly.